Circuit quantum electrodynamics with a structured vacuum

Patrick Harrington, Department of Physics, Washington University
October 6, 2017 at 4:00 pm
204 Crow
Event Description 

At sub-Kelvin temperatures, a single excitation can swap between the lowest energy levels of a superconducting circuit and one electromagnetic mode of a cavity—an interaction of light and matter regarded as a building block for quantum computation. Can we probe anything fewer than a single quantum excitation? The pristine electromagnetic vacuum itself has measurable effects on our circuit and offers a controllable resource for many-body physics. Similar to the Casimir effect, lossless electrical impedances impose boundary conditions on the vacuum modes, causing the electromagnetic environment to have vacuum fluctuations suppressed at certain frequencies. When the superconducting circuit simultaneously interacts with multiple vacuum modes, the circuit can decay to a superposition state rather than its usual ground state. In this seminar, I will explain the physics of the light-matter interaction for superconducting circuits and will present an experiment that dissipates our quantum circuit into a unique non-trivial state.